RFC861

Network Working Group J. Postel Request for Comments: 861 J. Reynolds

                                                                 ISI

Obsoletes: NIC 16239 May 1983

             TELNET EXTENDED OPTIONS - LIST OPTION

This RFC specifies a standard for the ARPA Internet community. Hosts on the ARPA Internet are expected to adopt and implement this standard.

Command Name and Code

EXTENDED-OPTIONS-LIST (EXOPL) 255

Command Meanings

IAC DO EXOPL

  The sender of this command REQUESTS that the receiver of this
  command begin negotiating, or confirms that the receiver of this
  command is expected to begin negotiating, TELNET options which are
  on the "Extended Options List".

IAC WILL EXOPL

  The sender of this command requests permission to begin
  negotiating, or confirms that it will begin negotiating, TELNET
  options which are on the "Extended Options List".

IAC WON'T EXOPL

  The sender of this command REFUSES to negotiate, or to continue
  negotiating, options on the "Extended Options List".

IAC DON'T EXOPL

  The sender of this command DEMANDS that the receiver conduct no
  further negotiation of options on the "Extended Options List".

IAC SB EXOPL <subcommand>

  The subcommand contains information required for the negotiation
  of an option of the "Extended Options List".  The format of the
  subcommand is discussed in section 5 below.

Default

WON'T EXOPL, DON'T EXOPL

  Negotiation of options on the "Extended Options List" is not
  permitted.

Motivation for the Option

Eventually, a 257th TELNET option will be needed. This option will extend the option list for another 256 options in a manner which is easy to implement. The option is proposed now, rather than later (probably much later), in order to reserve the option number (255).

An Abstract Description of the Option

The EXOPL option has five subcommand codes: WILL, WON'T, DO, DON'T, and SB. They have exactly the same meanings as the TELNET commands with the same names, and are used in exactly the same way. For consistency, these subcommand codes will have the same values as the TELNET command codes (250-254). Thus, the format for negotiating a specific option on the "Extended Options List" (once both parties have agreed to use it) is:

  IAC SB EXOPL DO/DON'T/WILL/WON'T/<option code> IAC SE

Once both sides have agreed to use the specific option specified by <option code>, subnegotiation may be required. In this case the format to be used is:

  IAC SB EXOPL SB <option code> <parameters> SE IAC SE